ci: add ability to dry-run release

[mkniewallner]

PR Checklist

• A description of the changes is added to the description of this PR.
• If there is a related issue, make sure it is linked to this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• If you've added or modified a feature, documentation in docs is updated

Description of changes

Add ability to manually trigger the release in dry-run mode (skipping upload and doc update steps). This will make it possible to test that we can build the wheels and source distribution properly before releasing, or when we do major changes to how they are built.

Tested in my fork, it works as expected (steps skipped on manual trigger, but not on real releases).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.0%. Comparing base (fc98954) to head (72339b2).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #802   +/-   ##
=====================================
  Coverage   93.0%   93.0%           
=====================================
  Files         37      37           
  Lines        961     961           
  Branches     173     173           
=====================================
  Hits         894     894           
  Misses        51      51           
  Partials      16      16           

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